Transmitter, Receiver, Transmitting Method, Receiving Method, Communication System, Communication Method, Program, and Computer-Readable Storage Medium

1. A transmitter comprising: means for acquiring transmission data; an encoder for outputting output sound data of a PCM format obtained by encoding the transmission data, the output sound data indicating sound in an inaudible frequency band; and a sound output unit for causing a DA converter to convert the output sound data so as to cause a speaker to output sound corresponding to the output sound data, wherein the encoder outputs the output sound data such that the output sound data indicates sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data such that each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude.

2. The transmitter according to claim 1 , wherein the encoder determines a time width of each of the plurality of sections with sound according to the transmission data and outputs output sound data indicating sound including the plurality of sections with sound.

3. The transmitter according to claim 2 , wherein the time width of each of the plurality of sections with sound is any one of a predetermined number of time widths set in advance.

4. The transmitter according to claim 1 , wherein the inaudible frequency band is equal to or higher than 20 kHz.

5. The transmitter according to claim 1 , further comprising a start control unit for causing the speaker to output sound indicating a start of communication to receiver and for changing the magnitude of the sound that the sound output unit causes the speaker to output based on sound input to a microphone, the sound being sound of the receiver responding to the sound indicating the start of the communication.

6. The transmitter according to claim 1 , further comprising a start control unit for causing, using the sound output unit, the speaker to output sound indicating a start of communication to receiver, and for, when sound of the receiver responding to the sound indicating the start of the communication is not recognized, changing magnitude of the sound that the sound output unit causes the speaker to output and causing the speaker to output the sound indicating the start of the communication to the receiver, repeatedly.

7. The transmitter according to any one of claim 1 , wherein the transmission data includes data indicating a payment account to be transmitted to a receiver.

8. The transmitter according to claim 7 , further comprising a payment-information acquiring unit for acquiring, based on a user ID, information indicating a payment account corresponding to the user ID via a network.

9. The transmitter according to claim 7 , wherein information indicating the payment account comprises encrypted balance information of the payment account.

10. The transmitter according to claim 9 , further comprising: a payment-result acquiring unit for acquiring, after the speaker outputs sound corresponding to the information indicating the payment account, payment result information including updated and encrypted balance information of the payment account from the receiver.

11. A transmitting method comprising: acquiring transmission data; outputting output sound data of a PCM format obtained by encoding the transmission data, the output sound data being output sound data indicating sound in an inaudible frequency band; and causing a DA converter to convert the output sound data so as to cause a speaker to output sound corresponding to the output sound data, wherein the output sound data is output such that the output sound data indicates sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data such that each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude.

12. A receiver comprising: a sound input unit for acquiring, via an AD converter, input sound data of a PCM format indicating sound in an inaudible frequency band input to a microphone and obtained by encoding transmission data, the sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data and wherein each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude; an extracting unit for generating extracted sound data obtained by extracting the sound in the inaudible frequency band from the sound indicated by the input sound data; and a decoder for decoding the transmission data based on the extracted sound data.

13. The receiver according to claim 12 , wherein the decoder decodes the transmission data based on length of time of each of the plurality of sections with sound indicated by the extracted sound data, the plurality of sections with sound being input to the microphone in order.

14. The receiver according to claim 12 , further comprising a start response unit for causing a speaker to output the sound input to the microphone, the sound indicating information for causing, when sound indicating that a transmitter starts communication satisfies a predetermined condition, the speaker to change magnitude of sound output by the transmitter.

15. The receiver according to claim 13 , wherein the transmission data includes data indicating a payment account, and the receiver further comprises: a payment inquiring unit for transmitting the data indicating the payment account and a payment amount to a balance management apparatus; and a result output unit for outputting information indicating a result of payment based on information indicating propriety of payment received from the balance management apparatus.

16. The receiver according to claim 15 , wherein the data indicating the payment account includes encrypted balance information of the payment account, and when information indicating payment permission is received from the balance management apparatus, the result output unit receives updated and encrypted balance information of the payment account from the balance management apparatus and transmits the received balance information to the mobile terminal.

17. The receiver according to claim 16 , further comprising a completion-information transmitting unit for transmitting information indicating payment completion to the balance management apparatus when information indicating that the balance information is received from the mobile terminal is received after the updated and encrypted balance information of the payment account is transmitted to the mobile terminal.

18. The receiver according to claim 15 , wherein, when information indicating payment permission is received from the balance management apparatus, the result output unit outputs, as information indicating a result of the payment, information for causing a speaker to output predetermined sound that a user can recognize.

19. A receiving method comprising: acquiring, via an AD converter, input sound data of a PCM format based on sound in an inaudible frequency band input to a microphone and obtained by encoding transmission data, the sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data and wherein each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude; generating extracted sound data obtained by extracting the sound in the inaudible frequency band from the sound indicated by the input sound data; and decoding the transmission data based on the extracted sound data.

20. A communication system comprising a transmitter and a receiver, the transmitter including: means for acquiring transmission data; an encoder for outputting output sound data of a PCM format obtained by encoding the transmission data, the output sound data indicating sound in an inaudible frequency band; and a sound output unit for causing a DA converter to convert the output sound data so as to cause a speaker to output sound corresponding to the output sound data, and the encoder outputting the output sound data such that the output sound data indicates sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data such that each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude, and the receiver including: a sound input unit for acquiring, via an AD converter, input sound data of a PCM format indicating sound output by the speaker and input to a microphone; an extracting unit for generating extracted sound data obtained by extracting the sound in the inaudible frequency band from the sound indicated by the input sound data; and a decoder for decoding the transmission data based on the extracted sound data.

21. A communication method comprising: acquiring transmission data; outputting output sound data of a PCM format obtained by encoding the transmission data, the output sound data indicating sound in an inaudible frequency band; causing a DA converter to convert the output sound data so as to cause a speaker to output sound corresponding to the output sound data; acquiring, via an AD converter, input sound data of a PCM format indicating sound output by the speaker and input to a microphone, generating extracted sound data obtained by extracting the sound in the inaudible frequency band from the sound indicated by the input sound data; and decoding the transmission data based on the extracted sound data, wherein the output sound data is output such that the output sound data indicates sound having a plurality of sections with sound and soundless sections between the adjacent sections with sound according to the transmission data such that each of the plurality of sections with sound include an envelope wherein the envelope is in the shape of a sine curve where an amplitude of the sine curve increases from a start time and decreases after reaching a maximum amplitude.